(1. ) Field of the Invention
The present invention generally relates to an evaporative fuel recovery apparatus, and more particularly to an evaporative fuel recovery apparatus in which fuel vapor, evaporated in a fuel tank, is returned back to the fuel tank via a vapor return passage between a canister and the fuel tank.
(2) Description of the Related Art
Generally, in an evaporative fuel control device, fuel vapor that is evaporated in a fuel tank is fed into a canister containing such an adsorbent as activated carbon, so that a certain amount of fuel vapor is adsorbed in the adsorbent of the canister, thus preventing the fuel vapor from escaping to the atmosphere. However, the quantity of fuel vapor that can be stored in the canister is limited as the capacity of the canister to store fuel vapor in the adsorbent is limited. When a great amount of fuel vapor is fed into the canister, the amount of the fuel vapor exceeds the capacity of the canister and the excessive vapor may escape from an opening of the canister to the atmosphere. In order to prevent the canister from having too much fuel vapor stored therein, it is desirable to use an evaporative fuel recovery device in which the fuel vapor is returned back to the fuel tank.
In the prior art, there is an evaporative fuel recovery device in which fuel vapor, evaporated in a fuel tank, is returned back to the fuel tank. Such a device is disclosed, for example, in Japanese Laid-Open Patent Application No. 61-257322. In this evaporative fuel recovery device, a vapor liquid separator for separating liquid fuel from fuel vapor is mounted in a vapor supply passage between a fuel tank and a canister, which passage connects the fuel tank to the canister so that fuel vapor can be supplied from the fuel tank to the canister. The liquid fuel separated by the separator is returned back to the fuel tank. However, in the above mentioned conventional device, it is necessary to additionally mount a vapor liquid separator in the vapor supply passage, and thus the structure of the evaporative fuel recovery device becomes complicated, and thus manufacturing costs increase. Also, in the case of the conventional device, there is a problem in that fuel vapor not liquefied due to the separator is not returned to the fuel tank but is instead fed to the canister, to be stored therein. The ability of the separator to separate liquid fuel from fuel vapor is not enough to recover the fuel due to the structure of the separator. Thus, it is difficult for the conventional device to efficiently return the fuel vapor back to the fuel tank, and thus it is not possible to prevent the canister from having too much fuel vapor stored therein.